ocfs2: fix NULL pointer dereference when traversing o2hb_all_regions
There may exist NULL pointer dereference in config_item_name() when one
volume (say Volume A) unmounts while another (say Volume B) mounting.
Volume A Volume B
already Mounted.
Unmounting, call
o2hb_heartbeat_group_drop_item()
-> config_item_put(item)
set reg(A)->item.ci_name to NULL
in function config_item_cleanup().
begin mounting, call
o2hb_region_pin() and tranverse all
regions. When reading
reg(A)->item.ci_name, it causes
NULL pointer dereference.
call o2hb_region_release() and
del reg(A) from list.
So we should skip accessing regions that is going to release when
tranverse o2hb_all_regions.
Signed-off-by: Yiwen Jiang <jiangyiwen@huawei.com> Signed-off-by: joyce <xuejiufei@huawei.com> Acked-by: Joel Becker <jlbec@evilplan.org> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Sunil Mushran <sunil.mushran@gmail.com> Cc: Jie Liu <jeff.liu@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>